Author Topic: Speed-Matched Locos as DPUs - How to Do It Right?  (Read 537 times)

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MK

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #15 on: February 26, 2019, 06:41:35 PM »
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I can't say that this is my experience.  Do you speed-match your fleet?  That may make a difference.  I haven't turned BEMF off in any of my locomotives, but I do have them all speed-matched to the following settings: CV2 at 1 smph, CV6 at 35 smph, and CV5 at 70 smph.

DFF

Yes, I do speed match those locos that I plan to run MU'ed.  99% of my fleet is Digitrax decoders.  I speed match the poor man's way, the three CVs, place them on an oval and eyeball the gap difference as they run.  I can never get them to be exact.  Increase one CV by 1 and it's a tad too fast.  Decrease the same CV by 1 and it's a tad too slow.  Maybe that's the reason why BEMF never worked for me.  I do better with BEMF off.

I am not doubting John's experience with ESU and Zimo but I don't have either and I'm afraid to get one ESU to try as I may never go back to Digitrax.   :scared:

Maybe samusi01 has a point since it sounds like he has extensive experience with both and has already done a mental comparison.

I've been playing around with momentum quite a bit in the last few months, mostly on ESU and Digitrax decoders, and I've been sorely disappointed with the Digitrax decoders, as results are quite variable and they don't even play well amongst themselves, let alone with other brands. On the other hand, ESU decoders are a snap to get to play well amongst themselves.

jdcolombo

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #16 on: February 26, 2019, 06:59:46 PM »
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I gave up on Digitrax decoders 20 years ago.  At the time, the best motor decoders I could easily get (and afford) were the Lenz Silver Mini series.  Since then, I've tried TCS, Soundtraxx, Zimo and ESU.  Zimo is the absolute best for motor control, IMHO, with ESU a close second.  If it wasn't for my preference for ESU sound over Zimo's sound decoders, I'd probably have an all Zimo fleet.  But all-ESU ain't bad, either.

And yes, I understand the monetary issues.  Every time I pulled a $100 Soundtraxx Tsunami decoder out of an engine and replaced it with an ESU LokSound Select Micro, I'd want to throw up.  But then seeing how the transplanted engines actually ran restored my appetite.  I don't ever want to do that again, however.

John C.

MK

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #17 on: February 26, 2019, 07:24:54 PM »
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I have too many Digitrax equipped locos to start going the ESU (sound or no sound) way.  Now I know how the older guys feel who has a ton of DC locos and DCC showed up 10/20/whatever years later.  Luckily for me, I re-entered MRR when DCC just showed up so I didn't have that DC/DCC dilema.

I only have the sound/no-sound predicament.  But I still follow your sound postings and videos.  :D

MetroRedLine

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #18 on: February 27, 2019, 12:43:47 AM »
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I think I could get away with DPU with some of my locomotives: one of the sets of power that I take to shows is four FVM GP60s, all with ESU decoders. It's quite neat to see how closely they perform when separated by a couple of inches.


If you want to be prototypically-correct, then only locos with AC traction are eligible for DPU duty: AC4400, ES44AC, ET44AC, SD70MAC, SD70ACe, SD70ACeT4. That's why you only see older locos in the lead consist (as your GP60s can do) and not in the middle or rear of the train.
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Maletrain

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #19 on: February 28, 2019, 09:39:46 AM »
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It seems like all of this assumes perfect electrical power supplied by the tracks throughout the run.  If one loco lurches due to dirt, transient short, relay-based reverser, etc., doesn't that tend to increase the probability of string-lining or accordioning the train?

Jbub

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #20 on: February 28, 2019, 10:29:09 AM »
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I'm curious on how much difference between truck mounted, body mounted mtl and true scale couplers there would be in using dpu's
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davefoxx

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #21 on: February 28, 2019, 10:34:42 AM »
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I'm curious on how much difference between truck mounted, body mounted mtl and true scale couplers there would be in using dpu's

I can't answer the question of body-mounted couplers versus True-Scale couplers, but I would not attempt mid-train or rear-of-train helper operations with truck-mounted couplers.  YMMV.

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conrad

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #22 on: February 28, 2019, 11:13:59 AM »
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I have too many Digitrax equipped locos to start going the ESU (sound or no sound) way.  Now I know how the older guys feel who has a ton of DC locos and DCC showed up 10/20/whatever years later.  Luckily for me, I re-entered MRR when DCC just showed up so I didn't have that DC/DCC dilema.

I only have the sound/no-sound predicament.  But I still follow your sound postings and videos.  :D

I come from the pre-DCC era and am still adding decoders to my locos.  Last year I bought 6 ESU LokPilot Nanos (53664) and put two into a pair of very old Lima Plymouth MDT switchers.  The ones that have a "circular" motor with drive gears machined to the inside flange of the driver wheels.  BUT, they run great and pull quite a few cars.  I'm now a fan of ESU and am waiting for my non-ESU  sound decoders to fail so I can install ESU ones.

conrad

jagged ben

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #23 on: February 28, 2019, 08:25:36 PM »
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If you want to be prototypically-correct, then only locos with AC traction are eligible for DPU duty: AC4400, ES44AC, ET44AC, SD70MAC, SD70ACe, SD70ACeT4. That's why you only see older locos in the lead consist (as your GP60s can do) and not in the middle or rear of the train.

I'm positive I saw Dash 9 DPUs on Tehachapi 11-13 years ago.  Research online confirms this.

https://www.trainorders.com/discussion/read.php?1,1610760

Apparently it has more to do with brake systems than traction motors, although the differences may largely coincide. 

jagged ben

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Re: Speed-Matched Locos as DPUs - How to Do It Right?
« Reply #24 on: February 28, 2019, 08:26:12 PM »
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It seems like all of this assumes perfect electrical power supplied by the tracks throughout the run.  If one loco lurches due to dirt, transient short, relay-based reverser, etc., doesn't that tend to increase the probability of string-lining or accordioning the train?

Yes that certainly adds to the fun.